O. Suttmann
J. F. Düsing
J. Koch
U. Stute
L. Overmeyer

Patterning and trimming of thin film strain sensors

International Conference of the European Society for Precision Engineering and Nanotechnology (euspen)
27.-31. Mai
Type: Konferenzbeitrag
Thin film strain sensors are capable of sensing mechanical loads in hostile environments and exhibit large longevity. Laser patterning is a promising approach to overcome existing restriction to 2-D surfaces due to existing manufacturing technologies. In order to fulfil the demand for a cost-efficient manufacturing process, a high throughput is required. At the same time, a high accuracy is required to realize a good signal/noise ratio by interconnection to a Wheatstone bridge. In a typical application the deviation of electric resistance values within a Wheatstone bridge should be better than 0.1 \%. This demand is satisfied through a two step process with the processing steps: laser patterning of the sensor layout and equalisation of the electric resitance value through a trimming process. We found an inverse proportional dependency between conductor width and deviation of resistance values within a sensor bridge after laser patterning. The resistor deviation could be decreased up to a factor of 15 by a subsequent trimming procedure. Laser patterning and trimming can be accomplished with the same machining setup. Thus, laser processing is a promising approach for manufacturing of thin film strain sensors on component surfaces with high throughput and a small number of processing steps.